1. Field of the Invention
The present invention pertains to a zoom lens system, and more particularly, to a compact zoom lens system that is suitable for use as a photo-taking lens in a video camera or single lens reflex camera.
2. Description of the Related Art
Conventionally, zoom lens systems comprising a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and at least one other lens unit have been known.
Among these zoom lens systems, those in which the first lens unit comprises at least three lenses and the second lens unit comprises at least two lenses have been proposed (e.g., U.S. Pat. No. 4,859,042).
Generally, in zoom lens systems, chromatic aberration must be adequately corrected in each lens unit. To do this, in a conventional zoom lens system, each lens unit must comprise at least two lenses having different dispersion values, which makes it extremely difficult to reduce the number of lenses in each lens unit and make the zoom lens system more compact.